1. Field of the Invention
This invention is related to gasoline engine detergents, and more particularly to gasoline intake valve deposit (IVD) inhibitor additives, i.e., agents which assist in preventing and removing deposits from intake valves and related parts of a gasoline combustion engine and to combustion chamber deposit (CCD) inhibitors.
2. Description of Related Information
The combustion of a hydrocarbon fuel in an internal combustion engine leads to the formation and accumulation of deposits on various parts of the combustion chamber as well as on the fuel intake and exhaust systems of the engine. The presence of deposits in the combustion chamber seriously reduces the operating efficiency of the engine. First, deposit accumulation within the combustion chamber inhibits heat transfer between the chamber and the engine cooling system. This leads to higher temperatures within the combustion chamber, resulting in increases in the end gas temperature of the incoming charge. Consequently, end gas auto-ignition occurs causing engine knock. In addition, the accumulation of deposits within the combustion chamber reduces the volume of the combustion zone, causing a higher than design compression ratio in the engine. This, in turn, can also lead to engine knocking. A knocking engine does not effectively utilize the energy of combustion. Moreover, a prolonged period of engine knocking can cause stress fatigue and wear in pistons, connecting rods, bearings and cam rods of the engine. The phenomenon noted is characteristic of gasoline powered internal combustion engines. It may be overcome by employing a higher octane gasoline, which resists knocking, for powering the engine. This need for a higher octane gasoline as mileage accumulates has become known as the engine octane requirement increase (ORI) phenomenon. It is particularly advantageous if engine ORI can be substantially reduced or eliminated by preventing or modifying deposit formation in the combustion chambers of the engine.
Another problem common to internal combustion engines is the formation of intake valve deposits. Intake valve deposits interfere with valve closing and eventually result in poor fuel economy. Such deposits interfere with valve motion and valve sealing, cause valve sticking, and, in addition, reduce volumetric efficiency of the engine and limit maximum power. Valve deposits are produced from the combustion of thermally and oxidatively unstable fuel or lubricating oil oxidation products. The hard carbonaceous deposits produced collect in the tubes and runners that are part of the exhaust gas recirculation (EGR) flow. These deposits are believed to be formed from exhaust particles which are subjected to rapid cooling while mixing with the air-fuel mixture. Reduced EGR flow can result in engine knock and in increased NO.sub.x emissions. It would therefore be desirable to provide a motor fuel composition which minimizes or overcomes the formation of intake valve deposits and subsequent valve sticking problems.
Both of the aforementioned problems have been addressed in the art. However, more effective and less costly solutions are always sought. An additional problem is introduced when both problems are attempted to be solved simultaneously. Frequently, an additive which reduces deposits in one area, will increase deposits in the other. For example, polyisobutylene amine (PIBA) based detergents provide intake valve deposit inhibition, but typically contribute to combustion chamber deposit buildup.
Co-assigned U.S. Pat. No. 5,234,478 describes a class of amido alkanolamines, obtained by reacting 4-alkyl-2-morpholinone with an alkylphenoxypolyoxyalkylene amine. These amido alkanolamines have potent combustion chamber and intake valve deposit inhibiting properties.
U.S. Pat. No. 4,832,702 describes a class of PIBA which provide intake valve deposit inhibiting properties. PIBA based detergents typically contribute to combustion chamber deposits, thereby limiting their usefulness.
An object of this invention is to provide a novel additive composition which may be employed in fuel compositions and particularly in a motor fuel composition.
Another object is to provide a fuel additive composition and a motor fuel composition which inhibits the formation of intake valve deposits in an internal combustion engine without contributing to CCD.
Another object of this invention is to provide a fuel additive and a fuel composition which inhibits or reduces the formation of combustion chamber deposits in an internal combustion engine.
Yet another object of this invention is to provide a concentrate composition which may be added to a motor fuel to provide motor fuel compositions of the instant invention.